This invention relates to liquid level control valves.
More particularly, this invention relates to a float actuated valve mechanism located in the sump area of a gas pressurized drain trap or the like where an accumulated condensate derived liquid is removed at a predetermined rate via an exhaust conduit controlled by the valve mechanism.
Prior art float actuated valves of the subject type provide a relatively constant mechanical advantage between a float and a valve plug or poppet movable in response to movement of the float. A relatively high mechanical force is required to initially move the valve plug from its associated seat due to the high internal pressure of the drain trap. Such a high mechanical force is unnecessary once an open condition has been established wherein a low pressure region is created at the valve plug-valve seat interface area, such low pressure region tending to aid the movement of the valve plug away from its associated valve seat. While a high mechanical advantage and accompanying high degree of float movement are needed to initially pull the valve plug away from its associated seat, such mechanical advantage is not needed once a predetermined opening position by the valve plug has been obtained. Prior art float actuated valve mechanisms having a constant mechanical advantage between the float and the valve plug provide unnecessary movement of the float in maintaining an open valve condition thus requiring float movement space that is unnecessary.
It would be desirable to provide a valve mechanism wherein the float moves a distance necessary only to establish and maintain necessary opening forces on the valve plug. Since unnecessary movement of the float would be eliminated, such a valve mechanism would be more economical from a space requirement standpoint.
In addition to the unnecessary space requirements of prior art float actuated valves, such valves often encounter problems in maintaining a positive seal between the valve plug and an elastomeric valve seat. Such problems often developed wherein the elastomeric valve seat would, over a period of time and successive operations, fail due to excessive deformation and cold flow of the elastomeric material caused in part by forces applied to the elastomeric valve seat by the valve plug.